Influence of the resonance in a gravity-gradient stabilized satellite

Using Hamiltonian formalism the translational-rotational motion of a satellite is studied near a resonance considering the orbital and rotational motions. A first order perturbation theory is derived by Hori's transformation in order to eliminate short and long periodic terms, preserving in the new Hamiltonian secular and resonant terms. This theory is again applied to study the resonant system whose analysis lead us to a system of equations equivalent to the equations of a simple pendulum which is integrable in terms of elliptical integrals.     

The Ultraviolet sky surveys: filling the gap in our view of the Universe

The GALEX mission is performing imaging and spectroscopic surveys of the sky at Ultraviolet wavelengths, and providing unprecedented sky maps in two UV bands, far-UV and near-UV, and catalogs of UV sources. I will describe the major surveys accomplished so far, and results in investigating the nature of the UV sources. The UV surveys, linked to a multi-wavelength archive, offer great sensitivity to detect and characterize several classes of astrophysical objects, such as low-redshift QSOs, star-forming galaxies, and white dwarfs (WD) in the Milky Way. Efforts towards obtaining a significant census of WDs from GALEX imaging data are described in particular. A dedicated, deep survey of nearby galaxies provides a snapshot of their recent star formation, shedding new light on the process of star formation and its modalities in different environments and conditions. Deep GALEX data revealed young stellar populations in extreme outskirts of spiral galaxies, previously thought to be stable against star formation given their low density. UV measurements for millions of nearby and distant galaxies map the history and probe the causes of star formation in the Universe over the redshift range z=0–2.     

可穿戴调绘记录仪研究

调绘是测绘生产中的重要工序。本文提出的可穿戴调绘记录仪能够实时记录视频、音频信息和GNSS轨迹坐标,并可响应语音命令,播报当前位置要素信息。该系统解决了平板调绘等操作不便的问题,解放了作业人员的双手,最大限度地保留了调绘时看到的信息,不需要质检人员到实地查看,节省了调绘作业的成本。     

A new analysis of the GJ581 extrasolar planetary system

We have done a new analysis of the available observations of the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the occurrence of aliases and the additional bodies??the planets f and g??announced in Vogt et?al. (Astrophys J 723:954?C965, 2010). Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the habitable zone (HZ) of the star GJ581. This region, for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period ??450?days, but we are judicious about any affirmation concerning this body because its signal is in the threshold of detection and the high period is in a spectral region where the occurrence of aliases is very common. Besides, we outline some dynamical features of the HZ with the dynamical map and point out the role played by some resonances laying there.     

Diversity and validity of stable-unstable transitions in the algorithmic weak stability boundary

This paper is devoted to verify the consistency of the algorithmic Weak Stability Boundary definition concerning the achievement of capture-escape detection, through examining the transitions produced by the implementation of this definition. Our main goal is to show that many types of spurious transitions concerning capture-escape behavior are found besides the expected transitions due to the separatrix role of the hyperbolic invariant manifolds of the central manifold of the collinear equilibria of the Planar Circular Restricted Three-Body Problem. We identify and characterize authentic and spurious transitions and discuss their spatial distribution along the boundary for sets of initial conditions with high eccentricity, showing the frequent occurrence of spurious transitions and of collisional trajectories. Also, we investigate smooth and fractal-like portions of the boundary. Finally, we propose an alternative stability boundary definition based on the effective detection of capture-escape transitions.     

Camacho inlet southern Brazil - Instability causes and user conflicts

Inlet stabilization is a common practice in Brazil, as it is worldwide. In this paper we present results of the analysis of the stabilization practices of the Camacho Inlet, located in Santa Catarina State, southern Brazil. This inlet is maintained intermittently, in accordance with a regime designed to benefit both local fishermen and rice farmers. Fishermen require this inlet to be open as a navigation channel during the fishing season; rice farmers needs it closed during the irrigation period to allow the pumping of fresh water from the Congonhas River which drains into the Camacho’s backbarrier lagoon. An additional complication arises from the tendency of this inlet to close naturally due to infilling by dune migration. Aerial images spanning a 65 year time period (1938-2003) were analyzed, demonstrating the variability in the inlet’s width between 0 (closed) and 360 m. The analysis of inlet stability and user needs indicate that an appropriate solution is the implementation of an annual inlet dredging program in the austral autumn. This would allow for the inlet to remain open from May to September and then close naturally for the rest of the year, providing for a backbarrier fresh water reservoir during the irrigation period.     

Binary collisions and the slingshot effect

We derive the equations for the gravity assist manoeuvre in the general 2D case without the constraints of circular planetary orbits or widely different masses as assumed by Broucke (AIAA/AAS 1988) and obtain the slingshot conditions and maximum energy gain for arbitrary mass ratios of two colliding rigid bodies. Using the geometric view developed in an earlier paper by the authors (Rica da Silva, A., Lemos, J.P.S.: Am. J. Phys. 74, 584–590, 2006) the possible trajectories are computed for both attractive or repulsive interactions yielding a further insight on the slingshot mechanics and its parametrization. . The general slingshot manoeuvre for arbitrary masses is explained as a particular case of the possible outcomes of attractive or repulsive binary collisions, and the correlation between asymptotic information and orbital parameters is obtained in general.     

Modelling the long-term distribution of significant wave height with the Beta and Gamma models

The paper suggests modelling the long-term distribution of significant wave height with the Gamma, Beta of the first and second kind models. The three models are interrelated, flexible and cover the three different tail types of Extreme Value Theory. They can be used simultaneously as a means of assessing the uncertainty effects that result from choosing equally plausible models with different tail types. This procedure is intended for those applications that require the long-term distribution of significant wave height as input rather than the prediction of extreme values. The models are fitted to some significant wave data as an illustration. Details about maximum likelihood estimation are given in A.     

后张力无粘结预应力高层建筑抗震可靠性研究

本文以天津市房地产开发（集团）河西友谊小区综合楼为研究对象,研究其在地震作用下高层建筑的可靠性,探索高层建筑结构系统的抗震可靠性分析方法,本文还对比一般框架梁柱结构与后张无粘结预应力板柱结构抗震可靠性的差异,研究层数变化时可靠性所受的影响,得到满意的结果。     

四川彭州市灯杆坡滑坡变形特征及稳定性分析

作者等对"5.12"汶川地震诱发的彭州市灯杆坡大型堆积体滑坡的变形破坏特征、滑坡的过程机制及震后稳定性进行了较系统的研究。滑坡变形可分为三个区,Ⅰ区为主变形区,Ⅱ和Ⅲ区为Ⅰ区后缘开裂诱发的向两侧的塌陷;滑坡Ⅰ区和Ⅱ区为推移式滑坡,Ⅲ区为牵引式滑坡,主滑Ⅰ区为沿基覆界面的推移式滑移,后缘开裂下错,中前部挤胀开裂;降雨和地震因素对滑坡稳定性影响较大,暴雨和地震情况下滑坡体处于欠稳定到不稳定状态,其中Ⅰ区中前部存在较严重的局部稳定性问题。